The field of the invention is headphones, and particularly, headphones in which a sealing cushion is provided to exclude external sounds from the ear of the user and/or improve the bass response of the headphone.
Numerous sealing cushions are known in the headphone and ear defender arts for providing a soundproof seal around the user's ears. When employed on an ear defender, a sealing cushion excludes external sounds, whereas when employed on a headphone the major objective is to improve coupling of low frequency sounds between the audio transducers and the user's ears. In either application, user comfort is an overriding factor since headphones and ear defenders may be worn for extended periods of time. Soft and resilient foam rubber and foam plastic cushions have been proposed as disclosed in U.S. Pat. Nos. 1,254,629; 1,514,152 and 3,593,341 and liquid filled cushions have been employed as disclosed in U.S. Pat. No. 2,801,423. Pneumatic cushions have been employed on a number of headphone products of the Koss Corporation in recent years.
Numerous conflicting objectives are imposed on the designer of a sealing cushion. The sealing cushion must be applied with pressure against the user's head in order to conform the sealing surface of the cushion with the contour of the head and yet it is this pressure which has in the past been the major cause of user discomfort. To alleviate this discomfort the sealing cushion can be constructed such that this pressure is not applied to the ear, but instead, to the surface area around the ear. Such "circumaural" sealing cushions are necessarily large and as a result, the headphone cup and supporting structure are also large. Increased size results in added weight which is another source of user discomfort.